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Video Game Effects 1
Running head: A SYNTHESIS OF VIDEO GAME EFFECTS
Examining the effects of video games from a psychological perspective:
Focus on violent games and a new synthesis
Douglas A. Gentile
Institute of Science and Society
Center for the Study of Violence
Iowa State University
National Institute on Media and the Family
Review prepared for the National Institute on Media and the Family
November, 2005
Author Note: Douglas A. Gentile is Assistant Professor of Psychology and Research Fellow at the Institute of Science and Society, Iowa State University; he is also director of research for the National Institute on Media and the Family. Portions of this manuscript have been reported in Gentile & Stone (in press). Correspondence concerning this manuscript should be addressed to Douglas A. Gentile, Iowa State University, Department of Psychology, W112 Lagomarcino Hall, Ames, IA 50011-3180. Phone: 515-294-1472; Fax: 515-294-6424; E-mail: [email protected]
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Examining the effects of video games from a psychological perspective:
Focus on violent games and a new synthesis During the late 19th century and throughout the 20th century, new types of mass media
were produced and consumed. Among others, these included dime novels, films, comic books,
radio, recorded music, television, video games, and the Internet. Each new medium was often
immediately praised for its potential benefits and reviled for its potential harms. For example, in
the 1880s, dime novels were claimed to have a “demoralizing influence upon the young mind,”
resulting in courtrooms being “thronged with infant criminals—with baby felons” (West, 1988,
12-13). Although opinions like these are quick to surface, and often get great attention from the
press, there are almost as many opinions as there are people who express them. How should one
know which opinions are credible? Science can help to provide the answer, by providing
empirically testable theories and facts about predictable patterns of behavior or opinion. This
paper has three goals: (1) to describe how scientific psychological research can be (and is)
conducted on the effects of video games, (2) to review the literature on the multiple effects of
video games, with an emphasis on violent games (because they have been the most controversial
and are also the most studied types of games), and (3) to provide a new synthesis describing four
dimensions along which video games may have important effects.
Video and computer games, like earlier media, were immediately lauded as potential
educational boons, and a great effort was launched to put computers into every classroom in
America in the 1980s. This drive gained great momentum, despite a paucity of evidence that
computers were more effective than (or even as effective as) more traditional educational
techniques. Simultaneously, United States Surgeon General Koop released a statement about the
dangers of video games (1982); this warning garnered attention despite a lack of scientific
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evidence for it at the time. The one benefit of these types of claims is that they provided an
impetus for scientists to begin studying the effects of video games (in this review, I define “video
games” to include console, computer, and arcade-based games). At the point of this writing,
scores of studies have been conducted on the various effects video games may have.
Unfortunately, there is still confusion about how scientific psychological research is conducted,
how to interpret it, and how strong it is.
The Role of Theory in Psychological Research
Scientific psychology has a long history of conducting media effects research, and a
longer history of conducting research on the effects of other stimuli on thoughts, feelings, and
behaviors. However, individual studies by themselves (and even groups of studies) can tell us
almost nothing without being grounded in a theory. The importance of theory cannot be
underestimated in psychological research. Although an individual study can provide facts about
a relationship between causes and effects, observed patterns of behavior cannot be fully
understood in the absence of a theoretical framework. For example, a study might demonstrate
that children who played a violent video game are more physically aggressive after playing than
are similar children who played a non-violent game. By itself, this finding is provocative, but
tells us little. Why did this occur? Is it a short-term or long-term effect? Was it a result of the
violence in the game, or of some other factor (such as frustration)? If it was the violence in the
game that caused the aggressive pattern of behavior, what is the mechanism by which the game
ultimately affects behaviors? That is, did the game increase overall arousal, or aggressive
emotions, or aggressive thoughts, or some other factor?
In psychology, no single study, taken alone, is ever considered to be definitive. In the
present example, a researcher might go on to propose a theory that explained how and why
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violent game play ultimately results in observable behavior differences (for example, by priming
aggressive thoughts). Additional studies would then be conducted to investigate whether violent
games actually do prime aggressive thoughts, and whether these thoughts “cause” the observed
increases in aggressive behaviors.
This is precisely how theories are so useful. They allow the formation of specific
predictions, and those predictions are empirically testable. If further studies reveal that violent
games prime thoughts, but that those thoughts don’t completely explain patterns of aggressive
behaviors, then the theory must be revised and tested again. This process allows for a rich and
detailed theory to be constructed based on empirically-derived facts, rather than on opinions.
”Exploratory” or atheoretical studies can be useful for discovering novel phenomena or
beginning a program of research. But by themselves, studies divorced from empirically-testable
theories are of little use because they have no context within which they can be understood.
The literature on video games has, to this point, lacked a broad theory within which to
interpret the many and varied types of results that have been found. This has often allowed the
dialogue over the effects of video games to be reduced to a question of whether video games are
“good” or “bad.” However, within specific domains, some very good theories have been
described and tested. I will describe briefly one of these domain-specific theories, the General
Aggression Model, and review some of the literature on violent video games. It is important to
note that, although this model has received considerable empirical support, it cannot explain
many other findings in the literature, such as why video games might improve visual attention
(e.g., Green & Bavelier, 2003), increase obesity (e.g., Vandewater, Shim, & Caplovitz, 2004),
lower school performance (e.g., Gentile, Lynch, Linder, & Walsh, 2004), or improve surgeons’
advanced laparoscopic surgical skills (Rosser et al., 2004).
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The General Aggression Model
The General Aggression Model is designed to predict both the short-term likelihood of an
individual engaging in an aggressive behavior, and also the long-term changes that increase the
likelihood of future aggressive behavior (see Anderson & Carnagey, 2004; Anderson, Gentile, &
Buckley, under contract; Anderson & Huesmann, 2003 for detailed descriptions). Figure 1
displays the basic short-term, or episodic, component of the model. In any given potentially
aggressive social encounter, there are both proximal and distal influences. The distal influences
include biological and environmental modifiers, which together influence aspects of people’s
personalities. A person’s personality includes many measurable dimensions (e.g., hostility) that
can increase or decrease the likelihood of aggression, and personality also influences the types of
situations that the individual is likely to encounter. Once in a given social situation (proximal
influence), aspects of both the person and the specifics of the situation combine to affect the
present internal state of the individual.
Under the parameters of the General Aggression Model, it is theorized that three aspects
of internal state can be affected (and are relevant for aggressive action): the current thoughts the
individual has (cognition), their feelings (affect), and their level of physiological arousal.
Assuming that person A has just been insulted by person B (a situational variable), person A will
likely have increased arousal (heart rate, blood pressure, stress hormones), increased negative
feelings, and perhaps increased aggressive thoughts. Before person A reacts behaviorally,
however, he/she goes through an appraisal and decision process. These processes include
immediate perceptions/reactions, and if person A does not have sufficient cognitive resources to
explicitly consider them, he/she will react immediately and impulsively. Even if there are
opportunities to consider the potential reactions, if the initial response is considered satisfactory
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or the potential consequences are not important, the impetuous action can occur immediately. If
the initial response is not satisfactory or the consequences might be important, then they can be
reappraised until a satisfactory response is decided upon, and the reaction will follow this delay.
This action changes the social encounter, characteristics of which, in turn, affect person and
situation variables, and the cycle continues.
This theory allows for a variety of specific hypotheses to be advanced and tested. For
example, it predicts that playing a violent video game (situational variable) might increase
aggressive thoughts, which in turn may increase automatic aggressive behaviors. This
hypothesis has been tested, and support has been found for it (e.g., Anderson, Carnagey,
Flanagan, Benjamin, Eubanks, & Valentine, 2004; Anderson, Gentile, & Buckley, under
contract).
The long-term aspects of the theory are shown in Figure 2, which displays many of the
personality variables believed to be influenced by an individual’s ongoing bio-social interactions.
What is learned across time depends on the experiences an individual has, including interactions
of experiences with biological factors (such as biological predispositions to learn certain types of
associations through rewards and punishments). Violent video games may affect individuals
over time by influencing their aggressive beliefs, schemata, and scripts, and by desensitizing
them to aggression. As children begin to see the world in aggressive terms and therefore begin
to act more aggressively, their personalities change to become more aggressive and hostile.
These changes will likely result in increased opportunities for aggressive behavior, because of
both changes in the individual’s personality variables and changes in the situations the individual
is likely to encounter as others react to the individual. Thus these experiences and changes over
time act as distal processes and causes of later aggressive encounters (Figure 1).
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Psychologists consider theory testing to be critical to evaluating research evidence. It is
not sufficient for studies to show some relation between video games and behavior. We must be
able to predict the relation, and explain why that relation exists. Every part (every box and arrow
in Figures 1 and 2) of the theory should be testable, and the theory must be revised as needed.
This process is crucial because no single study is ever conclusive. Each study has particular
strengths and weaknesses, and the goal of science is to test theories with many types of studies,
and keep refining the theories until it is possible to explain not only what happens, but why it
happens.
Types of Study Designs
In general, there are three dominant types of study designs, and each has distinct
strengths and weaknesses. They are experimental, cross-sectional (or correlational), and
longitudinal.1
Experimental Studies
The major strength of experimental studies is that causality can be determined. This is
done by randomly assigning participants to different groups, and treating each group identically
except for one variable (the “independent variable”). If the groups are shown to differ in some
measurable way (the “dependent variable”) at the end of the study, the most probable
explanation is that the independent variable caused the changes in the dependent variable. As
Anderson and his colleagues have argued (e.g., Anderson et al., under contract; Gentile &
Anderson, in press), in the case of experimental studies of violent video games, at least four
1 There are several taxonomies under which one could classify the different types of research designs. The three types discussed here are not exhaustive, but are the most typical and comprise the vast majority of media effects studies.
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characteristics serve as markers of high quality studies: adequate sample size (at least 200)2;
violent and nonviolent games equated on potentially confounding dimensions (e.g., difficulty or
frustration levels); violent and nonviolent games that are truly violent and nonviolent
(respectively); and a clear and valid measure of aggression or aggression-related variables
assessed for the game-playing participant. Over 30 independent experimental tests have been
conducted on the short-term effects of violent video games, yet few of them share all of these
features.
Table 1 displays the major results of experimental studies of video games on aggressive
affect (emotions), physiological arousal, aggressive cognitions, and aggressive behaviors. Many
have samples of fewer than 200 participants. Small samples make it much less likely that
researchers will find a significant difference, even where one really does exist. For example,
Funk, Buchman, Jenks, & Bechtoldt (2003) found no immediate effect of violent game play on
aggressive cognitions, but they reported that the observed power they have to find a significant
difference with a sample size of 66 is very small: 1-β = .10.4 Other studies may be criticized
because they present no evidence that the violent and nonviolent games are equated on difficulty
or other potentially confounded dimensions. Many did not match violent and non-violent games
on other confounding dimensions, such as frustration or fun, and others had no control game
(e.g., Calvert & Tan, 1994;Graybill, Kirsh, & Esselman, 1985; Irwin & Gross, 1995; Lightdale &
Prentice, 1994; Scott, 1995; Wingrove & Bond, 1998). Furthermore, some studies included
games that either were not really violent or included abstract violence against space ships rather 2 A sample size of 200 is needed to have sufficient power to detect effect of the size typically found in this literature (Anderson & Bushman, 2001). 4 Power (1-β) is defined as the odds of finding a statistically significant effect when one truly exists. This reported power can be interpreted as meaning that only 10 out of 100 studies with a sample size of 66 could find an effect – not good odds. Increasing the sample size makes it much more likely that an effect, if there is one, will be found.
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than violence against human figures (e.g., Anderson & Ford, 1986; Cooper & Mackie, 1986;
Hind, 1995; Winkel, Novak, & Hopson, 1987). Other studies reported measures that are only
tentatively related to aggression or relied on how “aggressively” participants played the game as
the measure of aggression (e.g., Ballard & Panee, 2001; Graybill et al., 1987; Hind, 1995;
Lightdale & Prentice, 1994; Van Schie & Wiegman, 1997). Still other studies have used
aggressive trait measures or self-reports of past aggression as the dependent measure of
aggressive behavior (e.g., Ballard & Wiest, 1996; Scott, 1995). Unfortunately, this is not a
complete list of methodological flaws found in this domain. For example, Graybill et al. (1987)
title their study “Effects of playing versus observing violent versus nonviolent video games on
children’s aggression,” but combined players and observers in their analyses. The first
experiment to include all four aspects of a high quality study was reported in 2000 (Anderson &
Dill).
Yet despite the various methodological flaws of individual studies, the vast majority still
document an increase in aggressive feelings, arousal, cognitions, and behaviors as a result of
violent video game play (as shown in Table 1). Because these are experimental studies, we are
able to conclude that violent games can cause increases in aggressive thoughts, feelings, and
behaviors. Most of these studies document only short-term effects (what happens immediately
post-play), although it is possible to design experimental studies to measure longer-term effects.
The major weakness of experimental studies is that researchers often rely on artificial
ways of testing what they wish to investigate. For example, it is unethical to allow participants
to hit each other as a measure of aggressive behavior. Thus, researchers use other means such as
the noise-blast paradigm (e.g., Anderson & Dill, 2000; Anderson et al., 2004; Persky &
Blascovich, 2004). It is then incumbent upon researchers to demonstrate that their laboratory
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measures have real-world validity. With the noise-blast paradigm, specifically, several studies
have shown that people who give higher blasts in the laboratory are also more likely to
physically aggress in the real world (e.g., Anderson & Bushman, 1997; Bernstein, Richardson, &
Hammock, 1987; Carlson, Marcus-Newhall, & Miller, 1989; Giancola & Zeichner, 1995).
Cross-Sectional Studies
Cross-sectional studies allow researchers to overcome the primary weakness of
experimental studies because they can use a wide range of “real world” measures of aggression.
Thus, researchers can study the relations between violent game exposure and several types and
severities of aggression. Cross-sectional studies can also incorporate multiple informants (e.g.,
self, peers, parents, teachers), thereby gaining additional levels of ecological validity. High
quality cross-sectional studies share several important characteristics: adequate sample size (at
least 200); a reliable measure of exposure to violent video games; and a reliable measure of
aggression or of an aggression-related variable (Anderson et al., under contract; Gentile &
Anderson, in press). The first published cross-sectional studies with all three of these
characteristics appeared in 2000 (Anderson & Dill, 2000; Colwell & Payne, 2000).
Table 2 displays the major results of a number of cross-sectional studies of video games
on aggressive affect, physiological arousal, aggressive cognitions, and aggressive behaviors.
Again, many have small samples. Many did not measure violence exposure, but only measured
total amount of video game play or amount of play of certain categories of games (e.g.,
Dominick, 1984; Farrar & Krcmar, under review; Fling et al., 1992; Lin & Lepper, 1987;
McClure & Mears, 1986). Several use questionable approaches to measuring aggression (e.g.,
McClure & Mears, 1986; Wingrove & Bond, 1998). Again, this is not a complete catalogue of
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methodological flaws, and despite them, the vast majority of these studies still document an
increase in aggressive feelings, arousal, cognitions, and behaviors (as shown in Table 2).
Because these are cross-sectional studies, we are able to conclude that violent games can
be related to serious aggression, such as aggressive delinquency and physical fights.
Furthermore, these relations are likely to be long-term relations rather than short-term relations.
The major weakness of cross-sectional studies is that causality cannot be determined. However,
correlational studies are important in that they can support, refine, or refute causal theories.
More importantly, cross-sectional studies are strong where experimental studies are weak, and
experimental studies are strong where cross-sectional studies are weak.
Longitudinal Studies
Longitudinal studies allow researchers to overcome some of the weaknesses of both
experimental and cross-sectional studies. In a longitudinal study, researchers study the same
people over a period of time. They can thus observe patterns of behavior and document both
short-term and long-term effects. Longitudinal studies can be either experimental or cross-
sectional in design, but even cross-sectional designs can provide some causal information, as it is
possible to determine what precedes what over time. The best longitudinal studies should share
the same characteristics of high quality experimental and cross-sectional studies.
To date, only four longitudinal studies of video game violence and aggression have been
conducted (Table 3). In one, 41 adolescents played either a hand-to-hand fighting game (Mortal
Kombat), a violent horror game (Resident Evil), or a sports game (NBA Live) once a week for
three weeks (Ballard, Panee, Engold, & Hamby, 2001). Physiological arousal (heart rate &
blood pressure) and emotions (facial smiling and disgust displays) were measured during play,
and self-reported anger, frustration, arousal, and relaxation were measured post-play. Heart rate,
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blood pressure, and facial displays of disgust decreased significantly over the three play periods,
showing desensitization with repeated exposure. Self-reported variables did not change
significantly, and there were no reported differences in desensitization by game type. However,
this study included a very small sample (only 13-14 playing each game), and only one hour of
play each week for three weeks.
In the second longitudinal study, 807 Japanese 5th and 6th graders were surveyed twice
during a school year (Ihori, Sakamoto, Kobayashi, & Kimura, 2003). The experimenters found
that the amount of video game play at Time 1 was significantly (but weakly, r = .08) related to
later physical aggression, but aggression at Time 1 was not related to later video game play.
However, the authors only measured the amount of video game play, and did not report whether
the children were playing violent games. This distinction between the amount and content of the
games is theoretically and empirically important, and will be discussed in greater detail later.
In the third study, 2,550 6th and 7th grade students were surveyed four times over two
years about their violent media consumption (action movies, video/computer games involving
weapons, and Internet sites describing/recommending violence), and their attitudes about and
engagement in aggressive behaviors (Slater, Henry, Swaim, & Anderson, 2003). The strength of
this approach is that it allows for a strong test of the mutual reinforcement hypothesis (i.e., that
aggressive kids seek out violent media, which in turn make them more aggressive, which makes
them seek out more violent media, which further increases their aggressive tendencies, etc.).
Indeed, this downward spiral is exactly the pattern that was found. However, this study also has
several problems – the most relevant here is that no data were reported for violent video games
independently, so it is impossible to determine the effect of violent games by themselves.
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However, the results are likely to be underestimates of the effects, because the measures used
were not sensitive measures of media violence exposure.
In the fourth longitudinal study, 213 gamers were recruited to play a massively
multiplayer online role playing game (MMORPG), 75 of whom were given the game which
included violent content (Williams & Skoric, 2005). Most of the gamers were adults (mean age
= 28, range 14-68). The experimental group were requested to play the game for at least 5 hours
per week for four weeks, although one third (32%) did not. At the beginning and end of the
month, all participants were given a normative beliefs about aggression survey, and were asked
to report whether they had been involved in a “serious argument” with a friend or a partner
during the previous month. There was no relation between game play and change in normative
beliefs in aggression. There were significant correlations between game play and both
arguments with friends and partners, but not with changes in arguments from time 1 to time 2.
Unfortunately, this study suffers from several critical flaws. The most important flaw is that the
researchers included no true measure of aggression. Arguments with friends and partners are
sometimes antisocial behavior, but are rarely aggression. When they are aggression, they are
typically characterized by verbal aggression. Violent video games typically model physical
aggression, not verbal aggression. Therefore, we would not expect them to have much effect on
verbal aggression. Furthermore, by only asking participants to self-report whether or not they
had been involved in arguments (yes/no), there was no way for this study to measure increases in
antisocial behaviors. If one had been involved in an argument at the beginning of the study and
also at the end, this study would have only been able to show no change.
However, there are many other flaws with this study. The study failed to find changes in
normative beliefs about aggression. However, these types of beliefs are trait-like – that is, they
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would only be expected to change over a long period of time, not within one month. It is true
that the measure used has been used in short-term experimental studies successfully, but in these
cases it is theorized that the effect is due to cognitive priming, rather than making long-term
changes in personal beliefs. Because the participants did not complete the survey immediately
after playing the violent game, we would not expect to see any effects on this measure.
Therefore, the failure to find an effect here is consistent with psychological theory and does not
suggest that violent games have no effect on beliefs.
The experimental and control groups were not treated equally, which is paramount for
being able to compare the groups at the end of the study. This resulted in differential attrition
rates (16% of the experimental group dropped out, compared to 51% of the control group).
Perhaps even more importantly, the researchers did not measure what games the control group
played during that month. It may be that they exceeded the experimental group in overall violent
video game exposure, although not by playing the particular experimental game.
Finally, there are significant questions yet to be answered about whether MMORPGs
would have the same effects as more traditional video games, even those in which one plays
against other gamers. They are far more social, and involve more non-violent strategy,
socializing, and prosocial cooperative behavior than typical violent first-person shooter games.
These types of games have not been shown previously to affect aggression in the short-term or
the long-term, so it is unclear why the authors expected to find an effect on antisocial behavior.5
In the fifth longitudinal study, 430 3rd, 4th, and 5th graders, their teachers, and their peers
were surveyed at two points during the school year (Anderson et al., under contract; Study 3).
Students who played more violent video games began to see the world in more aggressive ways
5 It appears from examining the dissertation on which the published manuscript was based that the study was also supported substantially by the video game publisher (providing 75 free copies of the game and a month of free access for the study participants), although this potential conflict of interest is never stated.
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(i.e., they had an increase in hostile attribution bias). Research has shown that children who
exhibit this cognitive bias (to assume that negative things happen due to hostile intent rather than
by accident) are far more likely to react aggressively (Bensley & Eenwyk, 2001; Crick, 1995;
1996; Crick & Dodge, 1994 ). Indeed, children who had high exposure to violent video games
changed over the school year to become more verbally aggressive, more physically aggressive,
and less prosocial (as rated by their peers and teachers; raw rs ranged between .24 and .40). It
appears that not only does repeated exposure to violent video games increase aggressive
behavior, but it also decreases empathic helpful behavior. This may be especially important
because increased aggressive behaviors and decreased prosocial behaviors also predicted peer
rejection (Anderson et al., under contract). This study has several strengths over the preceding
longitudinal studies, including more sensitive violence exposure measures and the use of
multiple informants. However, the lag time between the two surveys was relatively short,
ranging between two and six months.
Again, even with the different strengths and weaknesses of these studies, they also
document increases in aggressive cognitions and behaviors in connection with media violence
exposure (Table 3). Because these are longitudinal studies, we can make some claims about a
likely causal direction, as later behaviors cannot cause prior behaviors. However, unless the
studies are experimental in design, strong causal claims cannot be made.
Psychologists rarely put much weight on any single study, because each type of study has
distinct strengths and weaknesses. Ultimately, what psychologists look for is convergence in the
results of different studies using different methods and varied measures. If experimental, cross-
sectional, and longitudinal studies all point to the same conclusion, then the results become very
convincing.
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Meta-Analyses
There is yet one more tool scientific psychologists use to help draw general conclusions –
meta-analysis. This is a statistical technique, in which the data from many types of studies are
collected and analyzed together. This allows for conclusions to be reached that are not
dependent on any single methodology, population, or type of measurement. It also solves a
problem that is inherent in narrative reviews. Most narrative reviews only report published
studies. However, it is likely that some studies do not get published because the researchers
found no effect, and many journals have a bias against reporting studies with null results6. Meta-
analyses collect as many published and unpublished studies as can be found. Therefore, they are
an excellent test of whether an effect is “real” and how strong the effect is. (For an excellent
review of meta-analytic techniques related to media violence, see Comstock & Scharrer, 2003.)
Several meta-analyses have been conducted on violent video games (e.g., Anderson,
2004; Anderson & Bushman, 2001; Anderson, Carnagey, Flanagan, Benjamin, Eubanks, &
Valentine, 2004; Gentile & Anderson, 2003; Sherry, 2001). All of them have concluded that
there is a significant relation between violent video game play and aggression. Anderson and his
colleagues have conducted detailed analyses on five specific effects (e.g., Anderson & Bushman,
2001; Anderson et al., 2004). Across studies, violent video games have significant effects on
aggressive affect, physiological arousal, aggressive cognitions, and aggressive behaviors. They
are also significantly negatively related to prosocial behaviors. These conclusions hold for both
experimental and cross-sectional studies, so both causality and applicability to real-world
aggression can be inferred (., 2004). These conclusions also hold for studies with children and
adults (Gentile & Anderson, 2003). It would be expected that we might find larger effects with
6 This has sometimes been called the “file-drawer” problem, in that studies with null results are often relegated to one’s file drawers.
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newer studies since violent video games have become more violent over time. Indeed, this is the
pattern found, with earlier studies showing smaller effect sizes than more recent studies (Gentile
& Anderson, 2003). (However, this analysis is not entirely conclusive, because it may be that
newer studies find larger effects just because researchers have become better at measuring them.)
Finally, it could be argued that the pattern of effects is driven by methodologically flawed studies
– that is, poorer quality studies show a large effect, but high-quality studies show small or no
effects. Anderson et al. (2004) coded each of the studies included in the meta-analysis on nine
different quality dimensions, and the opposite pattern was found. Methodologically weaker
studies actually show significantly smaller effects of violent video games than do studies using
“best practices.”
Given the preponderance of evidence from all types of studies (experimental, cross-
sectional, longitudinal, and meta-analytic), it seems reasonable to conclude that violent video
games do indeed have an effect on aggression.
The Broader Context: Other Types of Video Game Effects
The preceding discussion is meant to describe how psychologists study the effects of
video games empirically, and what evidence is necessary to draw conclusions from those studies.
These methods have been used to document many other types of effects, some of which will be
discussed here..
School Performance
Several studies have documented negative correlations between video game use and
school performance for children, adolescents, and college students (e.g., Anderson & Dill, 2000;
Anderson et al., under contract; Creasey & Myers, 1986; Gentile et al., 2004; Harris & Williams,
1985; Lieberman, Chaffee, & Roberts, 1988; Roberts, Foehr, Rideout, & Brodie, 1999; van Schie
Video Game Effects 18
& Wiegman, 1997; Walsh, 2000). In general, a preponderance of studies shows a consistent
negative correlation between recreational video game play and school grades. Durkin and
Barber (2002) recently attempted to argue that there is no negative relation between video game
use and school grades (or many other variables). Specifically, they reported that students who
never use computers have lower grades (mean GPA = 2.53) than low use (2.79) and high use
(2.61) students (usage measured with a single 7-point Likert scale from “never” to “daily”). Yet,
they based these conclusions on survey data gathered in 1988, before games became particularly
violent, and when there was a strong relationship between computer use and socio-economic
status. That is, children from poorer families were far less likely to own computers in 1988.
Children from poorer families also typically have poorer school performance. Therefore, this is
not a fair comparison. A better test is whether the low use and high use groups differ, since both
groups come from families that own computers. Their data actually show that high use students
have significantly lower GPAs than low use students.7
These data notwithstanding, there is reason to expect that some types of computer use
may have positive effects on school performance. In one early study, Lieberman, Chafee, &
Roberts (1988) showed that children who use computers to play games perform more poorly in
school, whereas those who use computers for schoolwork perform better in school. Furthermore,
the belief in the benefits of educational software and video games (known as discrete educational
software) is so widespread that such software is second only to word processing software in its
availability and use in school classrooms (Murphy, Penuel, Means, Korbak, & Whaley, 2001).
Although the quality of research in this domain varies widely, meta-analyses of recent high
quality studies of the efficacy of discrete educational software show an effect size of .38
7 This confound completely changes the interpretation of their data, as it can explain why students who never use computers also have higher depressed mood, lower self-esteem, higher disobedience, substance use, and truancy, and lower GPAs than computer users. All of these relations would be predicted by lower SES.
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(Murphy et al., 2001). That is, there is a significant correlation between student use of
educational software and student achievement. The average correlation is .35 for educational
games teaching reading skills, and .45 for games teaching math skills. The efficacy for teaching
pre-reading skills may be even greater than for teaching reading skills. The average correlation
between educational software/games and reading skills is .44 for pre-kindergarten and
kindergarten children. These are large and potentially important effects, and show that video
games can be powerful and effective teachers.
Physical and Mental Health
Several studies have examined relations between video game play and various aspects of
physical health, although there has been no systematic attempt to organize or coordinate these
types of studies. Video games have been shown to teach children healthy skills for the self-care
of asthma and diabetes (Lieberman, 1997; 2001). These games have succeeded on multiple
levels, modifying the attitudes, skills, and behaviors that they were designed to teach. Recent
advances in virtual reality (VR) technology have also made it possible for physicians and
therapists to incorporate them into therapeutic programs. For example, several studies have
shown that VR programs can be effective in helping patients manage the pain of burns and
wound care, as well as desensitizing phobic patients to their fears, such as fear of heights, flying,
and spiders (Hoffman, 2004; Wiederhold & Wiederhold, 2005).
However, there are several studies documenting varied negative correlations between
video games and physical health. The amount of time American children spend in front of
electronic screens is considered by many to be an important environmental factor in the epidemic
of childhood obesity. Obesity has been called the most common health problem facing children
(Strauss & Knight, 1999), and its incidence has been increasing since the 1980s (Slyper, 1998).
Video Game Effects 20
Some research documents that the amount of time spent with video games can be linked to lower
activity levels, higher weight, and higher risk of obesity (Berkey et al., 2000; Subrahmanyam et
al., 2000; Vandewater, Shim, & Caplovitz, 2004).
A number of studies have documented video-induced epileptic seizures in some children
and adults (Graf, Chatrian, Glass, & Knauss, 1994; Kasteleijn-Nolst Trenite et al., 1999;
Badinand-Hubert et al., 1998). Research suggests that seizures can be activated by rapidly
flashing images (Ricci et al., 1998), and that games vary significantly in their likelihood to
activate seizures (Ricci & Vigevano, 1999). Although this is an unlikely occurrence for most
people, other physical ailments are more likely given the increasing amount of time children are
spending with video games. For example, there are a number of muscular and skeletal disorders
associated with heavy computer or video game use, such as tendonitis and nerve compression.
Indeed, there is even a form of tendonitis named “Nintendinitis,” caused by repeatedly pressing
game-controller buttons with one’s thumb (Brasington, 1990).
Skill Development
For many children, video games are an introduction to computer and information
technology. Playing games may afford a comfort level with computer interfaces and
input/output devices. For example, this author’s daughter understood the computer mouse terms
“point” and “click” by age three. Beyond this basic familiarity with technology, some
researchers have argued that video games are the “training wheels” for computer literacy (e.g.,
Subrahmanyam, Kraut, Greenfield, & Gross, 2000). Computer literacy includes skills beyond
traditional literacy skills, such as iconic (image representation and manipulation), spatial, and
visual attention skills. There is evidence that each of these skills can be affected by video games.
Video Game Effects 21
In a study with 206 undergraduates in the US and Italy, playing a video game for 2 ½
hours (Evolution or a memory game similar to Concentration) improved students’ ability to learn
iconic information about electric circuits compared to no game or physical memory game control
groups (Greenfield, Camaioni, Ercolani, Weiss, Lauber, & Perucchini, 1996). This is
particularly interesting, because the diagrams of electric circuits were completely unrelated to the
content of the video games played. Also, participants were more likely to answer questions
about electric circuits using iconic (rather than verbal) representations if they had played the
memory game on the computer rather than mechanically/physically.
Video games also have been shown to improve spatial skills. In one experimental study
with 61 5th graders, students played either Marble Madness, a game requiring the spatial skills of
guiding objects, judging speeds and distances, and intercepting objects, or Conjecture, a game
with word puzzles (Subrahmanyan & Greenfield, 1996). Students given 2 ½ hours of experience
with Marble Madness showed significant improvement in dynamic spatial skills (the change was
most pronounced in those who started out with relatively poorer skills), whereas those given the
same amount of experience with Conjecture did not improve. Okagaki & Frensch (1996)
reported two studies of undergraduates given 6 hours of practice on Tetris, a game that requires
spatial skills of mental rotation and spatial visualization. In the first, playing Tetris significantly
improved spatial performance on a paper-and-pencil test for men but not for women (compared
to a no video game control group). In the second, playing Tetris significantly improved spatial
performance on mental rotation and spatial visualization on a computer-administered test for
both men and women.
Greenfield, Brannon, & Lohr (1996) describe a cross-sectional study that suggests that
playing games using two-dimensional (2D) representations of three-dimensional (3D) space may
Video Game Effects 22
improve 2D-3D spatial skills. Skill playing The Empire Strikes Back, a game involving
navigating through 3D spaces, was correlated with mental paper-folding visualization skills.
With regard to visual attention skills, a study with college students to determine relative
ability to keep track of several different things on a computer screen at the same time (a skill
similar to those needed by flight controllers) concluded that expert video game players were
better at maintaining divided visual attention than were novices. In a second study, five hours of
playing a video game led to increased response speed in the visual attention task, regardless of
previous video game experience (Greenfield, deWinstanley, Kilpatrick, & Kaye, 1994). Other
studies have documented relations between video game play and visual selective attention
(Green & Bavelier, 2003), spatial visualization (Dorval & Pepin, 1986), mental rotation (De Lisi
& Wolford, 2002), and reaction times (Griffith, Volschin, Gibb, & Bailey, 1983).
Video games can also provide opportunities for practice in the use of motor skills. In a
study of college students, playing a golf video game improved students’ actual control of force
when putting, even though the video game gave no proprioceptive feedback on actual putting
movement or force (Fery & Ponserre, 2001). There have even been studies with adults showing
that experience with video games is related to better surgical skills (e.g., Rosser et al., 2004; Tsai
& Heinrichs, 1994).
Dimensional Approach to Video Game Effects
As described above, there are several video game effects research methods, and a wide
variety of effects have been documented. However, it has been difficult to understand this range
of effects, because they do not seem to be just one type of effect. Following the reasoning of
Gentile & Stone (in press), it is likely that there are at least four theoretically independent
dimensions along which video games can have effects: amount, content, form, and mechanics.
Video Game Effects 23
Amount
Many of the effects noted above appear to be primarily due to the amount of time one
spends with video games. These include the relations between video games and obesity,
muscular and skeletal disorders, and school performance. In fact, there is evidence that amount
has distinct effects independent of other types of effects. In path analyses with 607 8th and 9th
graders, total amount of time playing video games directly predicted poorer grades, but was not
directly related to antisocial or aggressive behaviors. However, playing violent games directly
predicted aggressive behaviors, but did not predict poorer school performance (Gentile et al.,
2004). Similarly, in the longitudinal study with 3rd through 5th graders, total amount directly
predicted poorer grades, but was not directly related to aggressive or prosocial behaviors
(Anderson et al, under contract). Conversely, playing violent games directly predicted increased
aggressive behaviors and reduced prosocial behaviors (a content effect, as described below), but
did not directly predict grades. These studies provide some evidence for the displacement
hypothesis, which predicts that electronic media can influence learning by taking the place of
other educational activities (Huston et al., 1992).
However, total amount may not be the only aspect of amount that matters – how children
distribute their time with video games may also enhance or reduce the effectiveness of learning
from them. Educational psychologists have shown that learning and transfer are most likely if
the learner practices some each day (distributed practice) rather than “cramming” – trying to
learn it all at once in one long session (massed practice). From an educational standpoint, video
games encourage a close-to-optimal combination of massed and distributed practice. Initial
attempts at the game provide immediate feedback and most people will keep playing until they
begin to show some progress. Such massed practice eventually begins to produce diminishing
Video Game Effects 24
returns (when a plateau is reached or fatigue sets in). However, the repetition will have begun to
develop both physical and mental skills on parts of the task. Each subsequent encounter with the
game provides memory benefits – namely, relearning anything that was forgotten, providing new
cues for memory, interpreting new information or examples with what is already in memory, and
reorganizing the memory accordingly. This combination of massed practice to build sufficient
initial mastery to play the game, followed by distributed practice over days or weeks is optimal
for learning (e.g., Ellis & Hunt, 1993; J. R. Anderson, 1983; Glaser, 1984). Although there is a
great deal of research on this aspect of repetition and amount in traditional education, there is
almost none with video games. In one study with middle school and college students, it was
hypothesized that if students play violent games (but not non-violent games) repeatedly over
long periods of time, then those students should show more aggressive cognitions and behaviors
(Gentile & Gentile, under review). This pattern was found, as students who distributed practice
over more days and years were more likely to evidence aggressive cognitions and behaviors, but
only if they played violent games. Among students who played fewer violent games, there was
no relation between distributed practice and aggressive variables.
Content
Most of the research on video games has documented what are likely to be effects of the
content of the games. Specifically, research on violent video games, educational video games
teaching reading or math skills, virtual reality programs helping to reduce phobias, and the
asthma and diabetes health promotion video games all document effects of game content. In the
case of educational games, these are intentional content effects; in the case of violent games,
these are unintentional content effects. As described above, there is evidence that violent content
has effects that are specific to aggressive and prosocial behaviors (Anderson et al., under
Video Game Effects 25
contract; Gentile et al., 2004), and that these effects are theoretically and empirically independent
of the effects of amount (although it should be noted that there is a significant correlation
between amount and violence exposure – people who spend a lot of time playing video games
also tend to be exposed to more violent content).
Form
There is a large body of literature with television and film on what are called “formal
features.” In general, this literature examines how people understand the formal conventions of
the medium and what they signify. For example, most people extract different meanings from
editing cuts and dissolves. If a couple goes through a door into a bedroom and the scene
gradually dissolves to the next morning, most people take a very different meaning away from it
than if the scene is simply (and abruptly) cut to the new scene the next morning. Similarly,
several of the studies on video games suggest patterns of effects that are not due to the content
per se, but to the form in which it is presented. Like the research on formal features in film and
television, there appear to be many features that are capable of differential effects, only three of
which will be discussed here.
First, some games require the use of 2D representations to provide 3D information and
navigation (O’Keefe & Zehnder, 2005). If players play these types of games, then we should be
able to document improvements in their ability to use 2D information for 3D navigation.
Although data are limited at this point, two studies suggest that these skills may be learnable and
show transfer. In the first of these, Greenfield et al. (1996) showed that skill in a game requiring
3D navigation was related to 3D mental visualization skill. Second, Rosser et al. (2004) showed
that demonstrated skill on video games and past experience with video games were the best
predictors of surgeons’ advanced laparoscopic surgical skills (laparoscopic surgery is a
Video Game Effects 26
minimally invasive set of procedures that include the insertion of a camera into the body; the
surgeon then operates from outside the body by looking at a video screen to direct his/her
motions). Surprisingly, video game experience and skill were better predictors of advanced
surgical techniques than either amount of medical training or number of laparoscopic surgeries
performed. These findings are difficult to explain using only amount or content types of
explanations, but seem to fit a form argument - that more experience with games leads to
increased skill in using 2D representations for 3D navigation.
Second, some games require constant scanning of the screen for information – for
example, in action games it is critical to be constantly scanning all parts of the screen because an
“enemy” could jump out from anywhere and a quick reaction is necessary. If players play these
types of games, then we should be able to document improvements in visual attention skills to
computer screens. This pattern has indeed been found, comparing different types of games that
require different types of attention (Green & Bavelier, 2003; Greenfield et al., 1994).
Third, some games portray their subjects with more realism than others. If players play
games with similar content, but with varied realism, then we should be able to document better
learning and transfer. There are few data to support this at the present time, but it makes
intuitive sense when considering simulation games. For example, if one wanted to learn to fly an
airplane, more realistic simulators should result in better learning that would transfer to outside
situations. Some results appear to suggest this may be correct, such as the finding that playing
Mortal Kombat with the “blood” setting turned on (so that injuries are accompanied by
depictions of spurts of blood from the body) led to greater increases in hostility and arousal than
with it turned off (Ballard & Wiest, 1996). In this study, the game content is equally violent in
both cases, but the form is different. Furthermore, in the meta-analysis described above
Video Game Effects 27
comparing date of study with the size of effect (Gentile & Anderson, 2003), effect sizes have
been increasing as games have been becoming more realistic. However, there may be many
other reasons for this result, so this interpretation should be viewed with caution. Certainly
gamers cite realism as one of the primary facets that are important to them (Wood, Griffiths,
Chappell, & Davies, 2004). Future studies will need to be conducted to determine the amount to
which realism (and what dimensions of realism) makes a difference.
Mechanics
The types of mechanical input/output devices used to play the games could also show
effects. If players play games with identical content, but with varied mechanical interfaces,
where some have increased similarity to “reality,” then researchers should be able to document
better learning and transfer. For example, playing a driving simulation game with a wheel and
pedals should improve driving skill more than playing the same game with a mouse and a
keyboard. Similarly, if surgical simulators are designed with input devices that are similar to
actual surgical instruments, then learning and transfer should be improved compared to input
devices with less verisimilitude. To date, no studies have been conducted to test this hypothesis.
This issue is further complicated because mechanics are not entirely independent from form.
Game movements are guided both by visual information gathered from the screen and use of the
input/output devices, and these inform each other (see Gibson, 1979, for a complete description
of how visual information, movement, and proprioception are linked). For example, in a first-
person shooter game such as Halo, gamers can often shoot at an enemy in a standard game view
or through a magnifying “scope” on the weapon. The optics are very different under these two
situations, as a small movement with the mouse changes what is seen on the screen a small
amount in the standard view, but a large amount when viewed through the scope. Research is
Video Game Effects 28
needed to determine how mechanics affect video game effects. However, the following anecdote
told to me by a graduate student suggests that something about mechanics is learned during game
play:
One evening, I was playing Halo with a group of friends. After we were done, we walked outside, and one of my friends yelled “Look out!” similar to the exchanges we had been shouting at each other during the game. Instead of ducking, or looking around, my right hand twitched to move the mouse to move me out of the way.
Conclusions
When attempting to understand all of the varied empirically-identified effects of video
games, conceptualizing the effects along the four dimensions of amount, content, form, and
mechanics is useful. There are at least two clear benefits to this dimensional approach to
understanding video game effects. First, it allows researchers and the public to move beyond the
dichotomous thinking that has too often characterized the debate around video games, in which
the discussion is reduced to a question of whether video games are good or bad. As the
preceding analysis shows, this is too simplistic a question. The same video game could have
both positive and negative effects, depending on what dimension one considers. For example,
playing the Grand Theft Auto series of games (in which one plays a criminal sociopath) a lot
each day could hamper school performance (amount effect), increase aggressive thoughts and
behaviors (content effect), improve visual attention skills (form effect), and improve driving skills
if one plays with a driver’s wheel and pedals or shooting skills if one plays using a gun
input/output device (mechanics effects).
Second, video games are increasingly being seen by several professions and industries as
valuable for training purposes. Until now, educationally motivated games have predominantly
focused on curricular aspects (the content). Although these have been successful, video game
designers may be able to cause even larger effects if all four dimensions are considered as the
Video Game Effects 29
games are designed. Consider an example of creating surgical simulators for training medical
students in laparoscopic techniques. Simulators should have maximum effect if each of the four
dimensions are planned.
1. Regarding amount, a certain amount of practice should be required, and it should be
distributed practice rather than massed practice.
2. Regarding content, the simulation should include as many variations, complications, and
potential errors as possible – in this way, knowledge can transfer across specific
examples.
3. Regarding form, the simulation should be as realistic as possible, including as many
variations in point of view as possible, and accurate 3D to 2D transformations (including
aberrations created by lens distortions).
4. Regarding mechanics, the simulator should include input devices that are similar to
surgical tools, and the reactivity shown in the form should be correct (that is, when a tool
is moved a small amount, the view should change appropriately).
In this example, the goal would be that when the surgeon is operating on a patient under real
pressures and time constraints, and she sees something wrong, she reacts quickly, proportionally,
and correctly. This type of automated reaction only comes with repeated exposure and
experience – something video games are extremely well designed to provide.
Video Game Effects 30
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Table 1: Experimental Studies of Violent Video Games on Affect, Arousal, Cognitions, and Behavior Experimental Studies on Affect Study N Age Major Findings Anderson & Ford (1986) 60 Undergrad Violent game led to increased hostility and anxiety, but not
depression Calvert & Tan (1994) 36 Undergrad No change in hostile feelings after playing V virtual reality (VR)
game (no NV control) Scott (1995) 117 Undergrad Non-linear increase in trait aggressiveness post play; no difference
in several personality variables Hind (1995) 102 15-18 years Incarcerated adolescents preferred playing games with aggressive
actions more than NV games and more than a non-incarcerated control group
Ballard & Wiest (1996) 30 Undergrad Play on Mortal Kombat with blood resulted in higher hostility scores than Mortal Kombat without blood, which in turn was higher than playing a NV game
Funk, Hagen, & Schimming 35 3rd-5th graders Higher, but non-significant, frustration levels after V game (1999) and parents Fleming & Rickwood 71 8-12 years V game increased state anger marginally significantly (p= .052), (2001) while simultaneously improving overall mood compared to a
paper-and-pencil task Ballard, Panee, Engold, 41 12-18 years V games increased frustration (but were harder to play than NV & Hamby (2001) game) Ballad & Panee (2001) 36 Undergrad Greater hostile feelings after playing a V game with aggressive
priming instructions compared to non-aggressive instructions Persky & Blascovich (2004) ? Undergrad Greater aggressive feelings after playing a V game, and greater
still if played in VR Farrar & Krcmar (under 227 Undergrad Playing V game increased state hostility review) Experimental Studies on Physiological Arousal Study N Age Major Findings Winkel, Novak, & Hopson 56 8th graders No effect of V or NV games on HR (1987) Calvert & Tan (1994) 36 Undergrad Increased HR playing V VR game compared to watching or resting Irwin & Gross (1995) 60 2nd graders No effect of V or NV games on HR Ballard & Wiest (1996) 30 Undergrad Play on Mortal Kombat with or without blood resulted in higher
HR and SBP (but not DBP) than playing a NV game Lynch (1999) 40 9th-12th grade V game play increased stress hormones (epinephrine & nor-
epinephrine) among hostile adolescents Fleming & Rickwood (2001)71 8-12 years V game increased HR and self-reported arousal compared to NV
game or pencil-and-paper game Ballard, Panee, Engold, 41 Adolescents V games increased frustration (but were harder to play than NV & Hamby (2001) game) Persky & Blascovich (2004) ? Undergrad Greater aggressive feelings after playing a V game in a VR envt,
compared to on computer or a NV game Matsuda & Hiraki (2003) ? Unknown Playing a V game (and some NV games) decreases prefrontal
cortex activation (indicating attention and less self monitoring) compared to other NV games and to just watching the games
Anderson, Carnagey, Flan- 130 Undergrad Playing V games increased BP compared to NV games, but agan, Benjamin, Eubanks, no differences in HR (although all games increased HR) &Valentine (2004)
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Experimental Studies on Aggressive Cognitions Study N Age Major Findings Graybill, Kirsch, & Essel- 116 2nd, 4th, & V game increased assertive fantasies and decreased defensive man (1985) 6th grade fantasies compared to NV game Graybill, Strawniak, Hunter, 79 7-11 years V games increased aggressive thought accessibility and liking & O’Leary (1987) compared to NV games Calvert & Tan (1994) 36 Undergrad Increased aggressive thoughts after playing V VR game compared
to watching or resting Kirsh (1998) 52 3rd-4th grade V game increased hostile attribution bias compared to NV game Anderson & Dill (2000) 210 Undergrad V game increased aggressive thoughts compared to matched NV
game Funk, Buchman, Myers, 35 8-12 years V game increased aggressive thoughts and decreased empathic & Jenks (2000) thoughts, but not significantly Tamborini, Eastin, Skal- 182 Undergrad V VR game (playing or watching) increased hostile thoughts ski, Lachlan, Feduik, compared to watching NV game & Brady (2001) Bushman & Anderson 224 Undergrad V game increased hostile expectations compared to NV game (2002) Funk, Buchman, Jenks, 31 5-7 years & No effect of V game on aggressive story completions or empathy & Bechtoldt (2003) 35 8-12 years Anderson, Carnagey, Flan- 130 Undergrad Playing V games increased aggressive thoughts compared to agan, Benjamin, Eu- NV games banks, &Valentine (2004) Anderson et al. (2004) 190 Undergrad Playing V game did not increase revenge motivation Anderson et al. (2004) 214 Undergrad Playing V game did not increase revenge motivation Bartholow, Sestir, & 107 Undergrad Davis (under review) Farrar & Krcmar (under 227 Undergrad Playing V game increased aggressive thoughts and intentions to review) verbally aggress, but not intentions to physically aggress Experimental Studies on Aggressive Behavior Study N Age Major Findings Cooper & Mackie (1986) 84 5th graders V game increased aggressive toy choice and play for girls, but not
aggressive or prosocial behavior (punishment & reward time) toward other children
Graybill, Strawniak, Hunter, 79 7-11 years V games did not decrease helpful and increase hurtful responses & O’Leary (1987) compared to NV games Chambers & Ascione (1987)160 3rd-4th & V games decreased prosocial (money donations) behaviors more 7th-8th grades more than NV game Silvern & Williamson (1987)28 4-6 years Increased aggressive behavior and decreased prosocial behavior in
free play after V game play or violent cartoon viewing (no NV control)
Winkel, Novak, & Hopson 56 8th graders No effect of V game on aggressive behavior (money deduction) (1987) Shutte, Malouff, Post- 31 5-7 years V game increased physically aggressive behaviors to children and Gorden, & Rodasta (1988) toys in free play Lightdale & Prentice (1994) 74 Undergrad Males played V game more aggressively than females when
introduced to opponents, but equally aggressively when opponents were anonymous
Irwin & Gross (1995) 60 2nd graders V game increased verbal and physical aggression to a peer in a frustrating situation and to toys in a free-play situation
Ballard & Lineberger (1999)119 Undergrad V game increased aggressive behavior (painful stimulus) and decreased prosocial behavior (lower reward) to confederate
Anderson & Dill (2000) 210 Undergrad V game increased aggressive behavior compared to matched NV game (noise blast)
Bartholow & Anderson 43 Undergrad V game increased aggressive behavior compared to NV game,
Video Game Effects 45
(2001) with men more affected than women (noise blast) Durkin & Barber (2002) 1,304 10th graders High computer game use correlated with greater aggressive
behavior compared to low computer game use Anderson et al. (2004) 190 Undergrad Playing V game increased aggressive behavior (noise blast) Anderson et al. (2004) 214 Undergrad Playing V game increased aggressive behavior (noise blast), red
blood did not increase aggression compared to green Persky & Blascovich (2004) ? Undergrad Greater aggressive behavior after playing a V game in a VR envt
compared to computer (noise blast) Bartholow, Sestir, & 92 Undergrad Playing V game increased aggressive behavior (noise blast) Davis (under review) Anderson, Gentile, & 615 9-12 years & Playing V E- and T-rated games increased aggressive behavior Buckley (under contract) 17-29 years (noise blast) Note: V = Violent, NV = Non-violent; VR = Virtual Reality; HR = Heart Rate, BP = Blood Pressure, SBP =
Systolic Blood Pressure, DBP = Diastolic Blood Pressure
Video Game Effects 46
Table 2: Cross-Sectional Studies of Violent Video Games on Affect, Arousal, Cognitions, and Behavior
Cross-sectional Studies on Affect Wingrove & Bond (1998) 23 Undergrad Game frustration led to increased discontentment and anxiety (no
NV or non-frustrating control) Durkin & Barber (2002) 1,304 10th graders High computer game use correlated with greater depressed mood
compared to low computer game use Anderson et al. (2004) 806 Undergrad Playing V games correlated with lower emotional susceptibility Bartholow, Sestir, & 107 Undergrad V game play correlated with increased hostility Davis (under review) Farrar & Krcmar (under 227 Undergrad Categorical game play not significantly related to hostility review) Anderson, Gentile, & 189 14-19 years V game play correlated with trait hostility and trait anger Buckley (under contract) Cross-sectional Studies on Physiological Arousal Ballad & Panee (2001) 36 Undergrad Higher use of aggression in game correlated with increased HR
and lowered SBP Cross-sectional Studies on Aggressive Cognitions Domonick (1984) 250 10th-11th grade Arcade game playing (but not home game playing) correlated with
aggressive cognitions Colwell & Payne (2000) 204 12-14 years Game exposure correlated with aggressive cognitions Anderson & Dill (2000) 227 Undergrad Greater violent game play correlated with aggressive personality Funk, Buchman, Myers, 35 8-12 years Naming a V game as favorite correlated with aggressive thoughts & Jenks (2000) Walsh (2000) 137 8th-12th grade Greater V game exposure correlated with physical fights Ballad & Panee (2001) 36 Undergrad Higher use of aggression in game correlated with increased HR
and lowered SBP Funk, Buchman, Jenks, 31 5-7 years & History of V game play correlated with lower empathy & Bechtoldt (2003) 35 8-12 years Funk, Baldacci, Pasold, & 150 4th & 5th grade Greater V game play positively correlated with proviolence Baumbardner (2004) attitudes and negatively correlated with empathy Krahé & Möller (2004) 231 8th grade Greater V game play positively correlated with acceptance of
physical aggression and indirectly with hostile attribution bias Gentile, Lynch, Linder, 607 8th & 9th grade Greater V game play positively correlated with trait hostility & Walsh (2004) Anderson et al. (2004) 190 Undergrad History of playing V games correlated with revenge motivation
and instrumental aggressive motivation Anderson et al. (2004) 806 Undergrad Playing V games correlated with positive attitudes toward
violence, lower agreeableness, lower conscientiousness, and higher narcissism
Bartholow, Sestir, & 107 Undergrad V game play correlated with lower empathy Davis (under review) Bartholow, Sestir, & 92 Undergrad V game play correlated with lower empathy Davis (under review) Farrar & Krcmar (under 227 Undergrad Categorical game play not significantly related to aggressive review) thought accessibility Anderson, Gentile, & 189 14-19 years V game play correlated with positive attitudes to violence in war, Buckley (under contract) attitudes toward intimate partner violence, and normative
aggression beliefs
Video Game Effects 47
Cross-sectional Studies on Aggressive Behavior Domonick (1984) 250 10th-11th grade Arcade game playing (but not home use) correlated with self-
reported physical aggression and aggressive delinquency McClure & Mears (1986) 290 9th-12th grade High-rate VG playing not correlated with psychopathic deviance or
neuroticism Lin & Lepper (1987) 189 4th–6th grade Arcade use of games (but not home use) correlated with teacher
ratings of impulsiveness and aggressiveness Fling, Smith, Rodriguez, 153 6th-12th grade Amount of VG play correlated with self-reported and teacher Thornton, Atkins, & ratings of aggressive behavior Nixon (1992) Funk & Buchman (1996) 357 7th & 8th grade For girls, but not boys, V game play associated with lower self-
esteem, poorer behavioral conduct, and other self-perceptions van Schie & Weigman 346 7th & 8th grade Greater amount of video game play negatively correlated with (1997) prosocial behavior but not significantly correlated with aggressive
behavior Weigman & van Schie 278 7th & 8th grade Greater amount of video game play and preference for violent (1998) games negatively correlated with prosocial behavior; preference,
but not amount, positively correlated with aggressive behavior Wingrove & Bond (1998) 23 Undergrad Game frustration led to increased negative feedback given to a
cooperative partner Colwell & Payne (2000) 204 12-14 years Game exposure correlated with aggressive behaviors Anderson & Dill (2000) 227 Undergrad Greater violent game play correlated with aggressive delinquent
behavior and non-aggressive delinquent behavior Funk, Buchman, & 364 4th & 5th grade Preference for violent games correlated with poorer behavioral Germann (2000) conduct (self-perception) Vandewater, Lee, & 225 7-12 years Family conflict correlated with increased V game play for girls, Shim (2001) but not for boys Colwell & Kato (2003) 509 12-14 years Amount of play and V game exposure predicted aggression in
samples of UK and Japanese adolescents Anderson et al. (2004) 214 Undergrad Playing V games & watching V TV correlated with aggressive
behavior (trait physical aggression) Anderson et al. (2004) 806 Undergrad Playing V games correlated with mild physical aggression, verbal
aggression, severe physical aggression Gentile, Lynch, Linder, 607 8th & 9th grade Greater V game play positively correlated with physical fights & Walsh (2004) after controlling for hostility Bartholow, Sestir, & 107 Undergrad V game play correlated with increased physical and verbal Davis (under review) aggression Bartholow, Sestir, & 92 Undergrad V game play correlated with increased physical and verbal Davis (under review) aggression Anderson, Gentile, & 615 9-12 years & V game play correlated with violent behavior Buckley (under contract) 17-29 years Anderson, Gentile, & 189 14-19 years V game play correlated with verbal and physical aggression Buckley (under contract) and violent behavior Note: V = Violent, NV = Non-violent; VR = Virtual Reality; HR = Heart Rate, BP = Blood Pressure, SBP =
Systolic Blood Pressure, DBP = Diastolic Blood Pressure
Video Game Effects 48
Table 3: Longitudinal Studies of Violent Video Games on Affect, Cognitions, and Behavior
Longitudinal Studies on Affect Ballard, Panee, Engold, 41 12-18 years Repeated play of V games (3 times over 3 weeks) resulted in lower & Hamby (2001) facial displays of disgust and smiling Ihori, Sakamoto, Kobay- 807 5th & 6th grade Increased amount of video game play (all play, not specifically V ashi, & Kimura (2003) games) related to later hostility Longitudinal Studies on Aggressive Cognitions Williams & Skoric (2005) 213 14-68 years Play of a violent MMORPG for one month did not increase normative beliefs about aggression Anderson, Gentile, & 430 3rd-5th grade V VG play early in a school year related to later increases in Buckley (under contract) hostile attribution bias after controlling for sex, race, total screen
time, parental involvement, and earlier hostile attribution bias Longitudinal Studies on Aggressive Behavior Ihori, Sakamoto, Kobay- 807 5th & 6th grade Increased amount of video game play related to later indirect ashi, & Kimura (2003) aggression (boys & girls) and later physical aggression (boys) Slater, Henry, Swaim, & 2,550 6th & 7th grade Media violence exposure (including video games) increases Anderson (2003) aggressive cognitions and behaviors, which in turn increase media
violence exposure, which increases aggressive cognitions & behaviors etc. over a two-year period (unable to separate out VGs)
Williams & Skoric (2005) 213 14-68 years Play of a violent MMORPG for one month was correlated with arguments with friends and with partners, but not with changes in arguments (although frequency of arguments was not measured appropriately to find changes)
Anderson, Gentile, & 430 3rd-5th grade V VG play early in a school year related to later increases in verbal Buckley (under contract) and physical aggression (as rated by self, peers, and teachers) after
controlling for sex, race, total screen time, hostile attribution bias, parental involvement, and earlier verbal and physical aggression
Note: V = Violent, NV = Non-violent; VR = Virtual Reality; HR = Heart Rate, BP = Blood Pressure, SBP =
Systolic Blood Pressure, DBP = Diastolic Blood Pressure, MMORPG = Massively Multiplayer Online Role-
Playing Games
Video Game Effects 49
Figure 1. The General Aggression Model: Distal and Proximal Influences on an Individual Social Episode
Biological Modifiers
Environmental Modifiers
Personality
Person Variables
Situation Variables
Social Encounter
Present Internal State
Affect
Cognition Arousal
Immediate Appraisal
Resources Sufficient?
Reappraisal
Outcome important & satisfying?
Thoughtful Action
Impulsive Action
Appraisal & Decision Processes
Yes Yes
No
No
Dis
tal I
nflu
ence
s In
divi
dual
Soc
ial E
piso
de
(Pro
xim
al In
fluen
ces)
Video Game Effects 50
Figure 2. The General Aggression Model: Long-Term Effects of Repeated Exposure to Violent Video Games
Present Internal State
Affect
Cognition Arousal
Repeated Violent Video Game Play Learning, rehearsal, & reinforcement of aggression-related knowledge structures
Person Variables e.g., Hostile personality
Situation Variables e.g., Peer group, social situations
Increase in aggressive personality
Aggressive perceptual schemata
Aggressive expectation schemata
Aggressive behavior scripts
Aggression desensitization
Aggressive beliefs & attitudes
Indi
vidu
al S
ocia
l Epi
sode
(P
roxi
mal
Influ
ence
s)
Rep
eate
d Le
arni
ng T
rials
acr
oss T
ime
(D
ista
l Inf
luen
ces)